Background: Pediatric injuries are among the most common psychologically traumatic experiences for children. Twenty million American children suffer from unintentional injuries annually. While the majority of these children display transient emotional distress, approximately 19% (i.e., 3.8 million) develop significant, persistent symptoms of posttraumatic stress disorder (PTSD). PTSD symptoms are key predictors of functional outcomes, may interfere with optimal adherence to medical regimens, and have been linked to poorer general health outcomes and impaired quality of life. Identification of variables that contribute to the development of PTSD is an essential step in maximizing the effectiveness of secondary prevention programs to reduce the incidence of PTSD in youth following medical events. Evidence suggests an association between parent and child PTSD but how parents' symptoms influence children's symptoms has not yet been established. Prior research has reported associations among cognitive appraisals about the traumatic event, coping behavior, and psychological recovery following injury. The ways in which parents influence children's appraisals and subsequent coping and how this affects PTSD outcomes is not articulated. While the relation of initial physiological reactions to the traumatic event with subsequent PTSD has been established, little research has examined the role of these reactions as they relate to peri-trauma cognitive appraisals in children and how assessment of these reactions could help in screening for PTSD risk. The proposed project will significantly deepen our understanding of the interplay among biological (cardiovascular levels), psychological (child's appraisals and coping), and environmental factors (how parents influence their child's appraisals and coping) and how these factors contribute to PTSD following pediatric injury. The specific aims are to 1) examine the roles of children's cognitive appraisals and coping during the peri-trauma injury period in predicting post- trauma child PTSD symptoms 2) elucidate the contribution of peri-trauma biological factors (i.e.,cardiovascular levels) as associated with peri-trauma cognitive appraisals to the development of PTSD post-trauma, and 3) determine parents' influence on their child's cognitive appraisals and coping by examining parent-child interactions during the peri-trauma period and how this predicts post-trauma child PTSD symptoms. Methods: In study 1, we will conduct secondary analyses of three existing data sets of pediatric injury samples to examine the influence of parent and child early trauma symptoms, child coping, and parent coping assistance in the development of child PTSD. We will use structural equation modeling techniques to examine cross-lagged regression models, latent growth curve models, and latent difference score models. In Study 2, we will combine 1) an innovative experimental design (adapted from the anxiety disorder literature), in which children (ages 7-13 years) and parents engage in an interaction task to appraise an ambiguous scenario and choose a coping strategy, 2) child and parent self-report of appraisals, coping, and PTSD symptoms during the peri-trauma period, and 3) medical chart review to obtain data on the child's heart rate and injury severity. Career Goals: This K23 Award will provide necessary training and mentorship for the candidate to become an independent pediatric psychology researcher and leader in the field of PTSD prevention by allowing the candidate to 1) gain expertise in research design and analyses of studies evaluating the interplay between biological, psychological, and environmental risk factors for PTSD among children who experience medical events and use of advanced statistical techniques (structural equation modeling) to examine predictors of PTSD, 2) develop new methodological skills as applied to the study and prevention of PTSD (observational coding for parent-child interactions), 3) gain expertise in development and testing of PTSD preventive interventions for children and parents during a period of acute medical stress (secondary prevention), and 4) advance scientific skills in publication of research in peer-reviewed scientific journals and grantsmanship. Importance: The goal of my future research program is to develop preventive interventions to reduce the incidence of PTSD in children following acute pediatric medical events. This proposed project advances The NIMH's Strategic Objectives to chart mental illness trajectories to determine when, where, and how to intervene by identifying malleable and robust risk factors and the proposed Healthy People 2020 goals to promote quality of life by testing strategies to promote adaptive coping and prevent the development of PTSD.